Bohr's correspondence principle for atomic transport calculations

TL;DR

This paper compares classical and quantum calculations of atomic diffusion in Fe-Cr alloys, demonstrating that larger atomic cells lead DFT results to align with classical CMS results, supporting the classical nature of atomic transport.

Contribution

It shows that increasing atomic cell size in DFT calculations causes results to approach classical CMS outcomes, highlighting the classical behavior of atomic diffusion in metals.

Findings

DFT results approach CMS results with larger atomic cells

Quantum coherence effects influence differences between methods

CMS calculations agree well with experimental data

Abstract

In this work we perform a comparison between Classical Molecular Static (CMS) and quantum Density Functional Theory (DFT) calculations in order to obtain the diffusion coefficients for diluted \emph{Fe-Cr} alloys. We show that, in accordance with Bohr's correspondence principle, as the size of the atomic cell (total number of atoms) is increased, quantum results with DFT approach to the classical ones obtained with CMS. Quantum coherence effects play a crucial role in the difference arising between CMS and DFT calculations. Also, thermal contact with the environment destroys quantum coherent effects making the classical behavior to emerge. Indeed, CMS calculations are in good agreement with available experimental data. We claim that, the atomic diffusion process in metals is a classical phenomena. Then, if reliable semi empirical potentials are available, a classical treatment of the atomic transport in metals is much convenient than DFT.